Magnetic resonance (MR)-based reporting methods, such as magnetic resonance imaging (MRI), offer certain known advantages as non-invasive methods. For example, MRI can be used at tissue depths where optical reporting methods can sometimes be complicated by light scattering and absorption by the tissue, e.g., tissue depths greater than about 250 μm.
One application of nanotechnology in medicine is the development of biocompatible nanomaterials as environmentally sensitive sensors and molecular imaging agents. Preparations of magnetic particles designed for separation and extraction use particles that are amenable to easy manipulation by weak applied magnetic fields. These materials are typically micron sized and have a high magnetic moment per particle. However, nanoparticles do not respond to the weak, magnetic fields of hand held magnets.